排序方式: 共有56条查询结果,搜索用时 125 毫秒
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The shockwave induced by surface direct-current (DC) arc discharge is investigated both experimentally and numer- ically. In the experiment, the shockwave generated by rapid gas heating is clearly observed from Schlieren images. The peak velocity of the shockwave is measured to be over 410 m/s; during its upright movement, it gradually falls to about 340 m/s; no remarkable difference is seen after changing the discharge voltage and the pulse frequency. In the modeling of the arc plasma, the arc domain is not simulated as a boundary condition with fixed temperature or pressure, but a source term with a time-varying input power density, which could better reflect the influence of the heating process. It is found that with a reference power density of 2.8× 1012 W/m2, the calculated peak velocity is higher than the measured one, but they quickly (in 30 Its) become agreed with each other. The peak velocity also rises while increasing the power density, the maximum velocity acquired in the simulation is over 468 m/s, which is expected to be effective for high speed flow control. 相似文献
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La1—xMxCoO3(M=Ca,Sr)表面状态的XPS研究 总被引:2,自引:0,他引:2
合成了一系列钙钛矿复合氧化物La_(1-x)M_(?)CoO_3(M=Ca,Sr),并用XPS研究了LaCoO_3中的La~(3+)部分被Ca~(2+)或Sr~(2+)取代后表面状态的变化。由XPS的O_(10)谱图拟合得到的吸附氧O(2)百分数与取代量x呈现规律性变化。对Ca_(2p)与Sr_(3d)谱图也进行峰拟合处理,其中结合能较高的Sr(2)、Ca(2)可指认为周围有氧离子缺位物种。Ca(2)或Sr(2)百分数与吸附氧百分数的关系可用取代后表面状态的变化来解释。 相似文献
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La1—xMxCoO3(M=Ca,Sr)还原性的研究 总被引:1,自引:0,他引:1
以XPS和XRD手段研究了La_(1-x)M_xCoO_3复合氧化物的还原性质,得到还原程度次序为La_(1-x)Sr_xCoO_3>La_(1-x)Ca_xCoO_3>LaCoO_3;相同离子取代系列随x增大,还原容易进行,探讨了取代钴酸镧的氢还原机理。 相似文献
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为了实现从室温到1000℃范围内的多点温度实时测量,基于红蓝宝石光纤传感探头,研制了一种连续快速温度测量的多通道光纤温度传感器.该系统结合了荧光测温和辐射测温原理,可同时测量8个传感探头的温度随时间的变化信号.提出基于面积平衡计算的数字迭代算法用来计算荧光寿命.与快速傅里叶变换算法的仿真对比结果表明,该算法计算速度快、抗噪声能力强、结果稳定性好、测量精度高.对系统进行长期的温度和稳定性实验,结果表明该系统具有较高的稳定性和测量精度,测温范围从室温到1000℃,精度达±1℃. 相似文献
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针对目前市场中的煤气报警器生产成本高和检测到煤气泄漏没有相应自动处理功能的问题,提出了多点自动检测、自动报警和自动排气的方案。本文设计了多检测点的无线传输电路,自动报警及自动排气电路。为了实现无线传输的目的,本文对无线传输的发送与接收程序进行了设计。通过软件仿真工具对煤气泄漏自动报警与自动排气装置的电路进行仿真与分析。实验结果,基于相同的一氧化碳检测指标要求,煤气泄漏自动报警与自动排气装置的硬件电路选用性能相对较差的一氧化碳传感器可以检测到一氧化碳的泄漏信号。实验结论,采用多点自动检测报警的措施降低了对传感器性能的要求,达到了降低成本的目的,自动排气功能增强了报警器的综合性能。 相似文献
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近年来,生物组装单元构筑微纳米结构的组装体在生物纳米技术等领域得到了广泛的研究。不同形貌的微纳米组装体可以通过生物分子的自组装这样快速、简便的方法获得。在众多肽基构筑基元中,二苯丙氨酸二肽及其衍生物作为一种生物活性的肽,具有生物兼容性好、容易化学修饰/生物功能化、制备简单等特点,是构筑微纳米结构材料时重要的生物基元之一。通过可控的方法组装,可以得到基于二苯丙氨酸及其衍生物的不同结构的组装体,他们在光学、机械工程、电化学传感检测等方面也具有广阔的应用前景。研究证明通过改变组装条件以及引入外源小分子等方法可以实现调控短肽的分子组装。本文综述了二苯丙氨酸二肽微纳米组装体的可控组装及他们在生物医学、生物传感、光电材料、光波导和催化等方面的应用。 相似文献
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Electric and plasma characteristics of RF discharge plasma actuation under varying pressures 下载免费PDF全文
The electric and plasma characteristics of RF discharge plasma actuation under varying pressure have been investigated experimentally. As the pressure increases, the shapes of charge–voltage Lissajous curves vary, and the discharge energy increases. The emission spectra show significant difference as the pressure varies. When the pressure is 1000 Pa,the electron temperature is estimated to be 4.139 e V, the electron density and the vibrational temperature of plasma are peak4.71×10~(11)cm~(-3) and 1.27 e V, respectively. The ratio of spectral lines I391.4/peak I380.5which describes the electron temperature hardly changes when the pressure varies between 5000–30000 Pa, while it increases remarkably with the pressure below 5000 Pa, indicating a transition from filamentary discharge to glow discharge. The characteristics of emission spectrum are obviously influenced by the loading power. With more loading power, both of the illumination and emission spectrum intensity increase at 10000 Pa. The pin–pin electrode RF discharge is arc-like at power higher than 33 W, which results in a macroscopic air temperature increase. 相似文献